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while I have been slowly developing the long cranking and driveability issues I have, I was also working on fabricating and working with the sound of a custom exhaust for my 760Li.

I wanted to try to compile this into one nice, video like a documentary, but it's too time consuming right now.

Target sound was something more like a V-12 Lambo or Ferrari by trying to enhance the upper harmonics of the V-12 engine (the V-12 shriek, as I call it), instead of just strapping on yet another polished, stainless fart can that's all bass and painful drone and no real sound quality at all.

If you like a deep deep rumble, that's fine, but this exhaust sound on the V-12 is not for you. I tested a few other mufflers and found that the typical large can with fiberglass matting in it and perf tube gives that low rumble, which is not what I wanted. If you were to modify any expensive after market 745 exhaust to work on your 760, it would not sound like this at all.

FWIW, I tried the Mufflerman style treatment of the stock flapper valve on the end of a straight pipe, but found it does not work that well for V12s. The resulting sound is too small and has no V-12 character. Sounds great on V8s though.

First thing I did was to simply undo the exhaust to see how the engine sounded with no exhaust.

here's the stock cats with the entire exhaust loosened and hanging off a couple of inches. Not my favorite sound to send down some straight pipes. Gives you an idea of what the V12 would sound like with open pipes and no exhaust sound-tuning at all.

here's the best sound "I" could come up with that's close to just straight pipes, but more civilized and with the V-12 shriek. It's the stock resonators (the long BMW tubular mufflers by the transmission) with nothing but two 2.5" straight pipes after them. It is interesting because usually perforated tube mufflers remove highs and mids. This still has some V-12 shriek with good higher harmonics. I like it, but it's too loud.

I liked that sound so much, I just wanted to shrink it down so it was not as loud. I used a small, open chamber muffler on each tube that would cut bass almost completely, and also possibly, enhance mids a bit. After reviewing a ton of videos online, and having some experience making some exhaust systems for 300zxs, I decided for the first time to gamble on a pair of Flowmaster Super 10s (barf, I know--Flowmasters, but I kinda knew they would work), with some 14" long bent tips. I also tried the Flowmaster DBXs and they sounded good with the below "long turn-down tips"--with NO stock BMW resonators at all. But, they don't fit anywhere under the car. So I could fit the Super 10s with their long turn-down tubes in the rear muffler cavity and use the BMW resonators, and get the sound I wanted.

If you don't use the tips, or use really short tips, but don't use long tips, they sound all bass-ey. I think they sound horrible with short or no tips. The long bent tips MAKE the sound for me. I even tried cutting their length by only 2" and lost a bunch of V-12 shriek--it started to shift the resonant pitch down. Watch what happens when the tip blows off during the clamped-on test. The muffler goes from V-12 shriek to fart can rumble.

this GoPro video is interesting. It has a good race-y quality to it, but since the mike is so close, it loses the higher-pitched harmonics just a bit, but still shows a good side of the exhaust sound, if that is the sound you like.

The movies show a bunch of clamped together test rigging that is all ghetto and loose. it's now all welded up with flanges and such and stays put. Also, the tips are tucked in under the bumper about another 1.5".

The next plan is to replace the two, clamped on turn-down tips with stainless bends. My only bit of bling.

So, 260 views of this thread at this point and not one comment. Now that I am done dealing with my emergency HPFP issues, I plan to clean the exhaust up, powdercoat it, and make some nicer tips. I mean, I like the sound, all my pals who hear it live, like the sound. One is so over the moon about it he tells me the videos don't do the sound justice.

Nice videos! Interesting how everyone has different preferences of what they like, personally, I like mine to be as quiet as possible. Maybe that way I can hear when I think something is going wrong. Then again I should maybe make it louder to remove some of my paranoia over every little sound lol.

after getting the video's to load, I do have to say that does sound pretty dang good! I would love to see photos of the setup you have and maybe even try to start a thread on how to change the exhaust from that point!

****, I'd probably extend the warranty on my 760 if I could get a sound like yours, but with the lower rumble/growl!

I'm trying to load the youtube video's now (buffering issues) but it sounds a lot better than it does from the factory. Do you have a picture of the final product?

I'd be interested in replicating this, but with a little more emphasis on the growl of the V12 and then having the change over to the high pitch scream/shriek that a V12 gives off.

I'm not sure if you have ever removed your airboxes before, but only our N73 airboxes have the "auxilliary air flap". It enhances engine growl at WOT, by opening the flapper to send us some sound in the cabin (also sucks hot air from the engine bay).

If your vacuum tubes are not working, or separated, which happens a lot, then you will miss some of this. It will not set a SES light, but it will code in INPA or DIS. You could stick them open permanently and get more growl all the time. For me, I'm not as much a fan of the engine growl, and even disabled it on my 135K motor, but on the fully functioning 50K motor it does not sound bad. Sounds fresher.

I found the more straight the pipe and muffler system was, the more smooth and ghostly it was, the more I kinked the pipes or used small chamber-like mufflers, the more "rat" and growl I got.

you need to find a way to cut the 2-3' long bass waves and allow the upper harmonics to shine. Magnaflow type mufflers will not do this. They will enhance bass waves even more.

then he removed a perforated tube fiberglass-packed resonator and added a perforated tube fiberglass-packed resonator. he could have left the first stock resonators on and ran straight or X-pipe, and my guess is: it would sound very similar. But he would not have the cool mufflers in back so I can understand the configuration of mufflers in back.

then he did something more like what I did, acoustically. He still has glass-packed resonating in the cans (which is what my stock resonators do), but also, redirecting the flow, in a chamber, which is what my Flowmasters do. That was the point of this project: to cut bass and allow the rest of the exhaust sound to speak. Chambers do that.

The only thing I did not do was an X-pipe. I have the bends to weld one up. I have thought about it. I am not sure I want to do it, but from talking to the Flowmaster people, they claim an X-pipe usually cuts bass out, which is what I want. Again, they have little or no experience with V-12s. The young kid I was talking to was probably repeating what the boss told him to say. He could not remember the last time he advised someone on a V-12 system.

The main reason for doing X-pipes in the first place is to try to remedy the uneven firing and uneven exhaust scavenging of V-8 race motors with headers. Most V-12s fire evenly and don't "need" a X-pipe for any reason, other than to mix the sound of the two sides together. It won't help performance, and certainly won't help unless you are running some tuned long headers.

If you want that sound for your v12, do that recipe. If you want a more mellow and high-pitched tone, use my recipe or something similar. That Aston could sound very different with a stock or other different exhaust.

If you like my approach, avoid the use of any muffler that looks like this inside.

****, I'd probably extend the warranty on my 760 if I could get a sound like yours, but with the lower rumble/growl!

This is a great quote, and what i was trying to get going with the V-12 crowd: a "conversation" about how to get our cars some "soul".

I've noticed that even the 745LIs with full rear comfort, have a great V-8 growl-- stock-- and sound like they have a soul of some kind, but the V-12 I think, simply fell through the cracks from a BMW tuning standpoint.

yes yes, all my pals say:, but it's supposed to be quiet, it's a LIMOUSINE. To them, I remind them that the 745LIs (which are also Limos) still have a great sound, it's only the V-12s that seem to have no aim to their sound, as stock.

hopefully, one or two of the videos where I remove one or two items and expose what's still left, will get someone to try another experiment with the N73 exhaust.

Also, I found it was difficult to fit two aftermarket mufflers in the muffler bay, but one big one and a 3.5" pipe in and out, might be a way to go. You could try a few different mufflers and get the sound you want.

So, 260 views of this thread at this point and not one comment. Now that I am done dealing with my emergency HPFP issues, I plan to clean the exhaust up, powdercoat it, and make some nicer tips. I mean, I like the sound, all my pals who hear it live, like the sound. One is so over the moon about it he tells me the videos don't do the sound justice.

No V12 owners out there with an opinion? (flame suit on...)

Just saw it today. Great work. viewing on my IPad so sound sucks. Will open on Bose to get full effect later.

Only point is I agree that having it sound like a Lamborghini would be great.However most American Muscle heads don't know what a V12 or a 4 cylinder Indy cars sound like. So all your hard work will fall on Tone Deaf Ears.

I'm not sure if you have ever removed your airboxes before, but only our N73 airboxes have the "auxilliary air flap". It enhances engine growl at WOT, by opening the flapper to send us some sound in the cabin (also sucks hot air from the engine bay).

If your vacuum tubes are not working, or separated, which happens a lot, then you will miss some of this. It will not set a SES light, but it will code in INPA or DIS. You could stick them open permanently and get more growl all the time. For me, I'm not as much a fan of the engine growl, and even disabled it on my 135K motor, but on the fully functioning 50K motor it does not sound bad. Sounds fresher.

I found the more straight the pipe and muffler system was, the more smooth and ghostly it was, the more I kinked the pipes or used small chamber-like mufflers, the more "rat" and growl I got.

you need to find a way to cut the 2-3' long bass waves and allow the upper harmonics to shine. Magnaflow type mufflers will not do this. They will enhance bass waves even more.

I haven't yet but I'll look at the flapper/airbox design and see if I can come up with some sort of way to enhance the sound and limit the amount of hot air the engine is getting from the flap!

when you say "rat" describing the sound, I'm not quite understanding what you mean. Can you elaborate a little bit more so I can understand?

I'd like a nice deep section to the exhaust, however nothing to loud or drone filled or something with too much bass. As well I'd like something subdued and not screaming "look at me" if I decide to floor it and pass someone.

Quote:

Originally Posted by mws

Oh good I found a link. I have been in a DB9 with this exhaust. My pal who did this to his car, loved the sound. I could not stand it, frankly. This is NOT the sound I want.

This is what a V12 sounds like with:

headers (we don't have headers)

straight pipes off the cats, no stock resonators (probably also no cats)

If you want that sound for your v12, do that recipe. If you want a more mellow and high-pitched tone, use my recipe or something similar. That Aston could sound very different with a stock or other different exhaust.

If you like my approach, avoid the use of any muffler that looks like this inside.

This is a great quote, and what i was trying to get going with the V-12 crowd: a "conversation" about how to get our cars some "soul".

I've noticed that even the 745LIs with full rear comfort, have a great V-8 growl-- stock-- and sound like they have a soul of some kind, but the V-12 I think, simply fell through the cracks from a BMW tuning standpoint.

yes yes, all my pals say:, but it's supposed to be quiet, it's a LIMOUSINE. To them, I remind them that the 745LIs (which are also Limos) still have a great sound, it's only the V-12s that seem to have no aim to their sound, as stock.

hopefully, one or two of the videos where I remove one or two items and expose what's still left, will get someone to try another experiment with the N73 exhaust.

Also, I found it was difficult to fit two aftermarket mufflers in the muffler bay, but one big one and a 3.5" pipe in and out, might be a way to go. You could try a few different mufflers and get the sound you want.

Honestly, I was thinking about having straight pipes to the center of the car which would have some resonators to reduce drone/bass tones and then add a muffler to help quiet it down but still retain the growl. If I can find a youtube video of the sound I'm looking for I'll post it

csmeance, I was going to respond with some particulars, but I am a bit confused about the sound you want.

let's look at it this way: what aspects of the sound I came up with do you like? what is missing?

what aspects of the Aston youtube video do you like? what is missing?

to answer your question about "ratty", to me the Aston sounds "ratty" "blatty" "splattery". Whatever you want to call it. Bright, like a wet fart or someone playing one of those damned soccer horns in a stadium. I don't like that bright blatty sound.

csmeance. I am more awake now and after reading this I can suggest some ideas:

I have a background as a trombone player. So I have played for years in symphonic bands and understand the whole "tubing size and length and how it effects sound" thing. I also worked for years as a sound engineer both live, and mostly in the studio, using EQ and other processors to filter sound. I also spent years applying filters on synthesizers, starting with the Moog, and then a prophet 5 and then a Yamaha DX7. All; very different beasts. The point is, you tweak and try different filters, which subtract sound, or in some cases, add sound with another operator or oscillator, until you get what you want.

Along those lines, I also have made exhausts for a few different cars. Most V6s, and one rotary BUT.... never had the time or money to play with the components to "tune" the sound like in the studio or like a synthesizer. I always went for the best flow, and usually was not thrilled with the sound.

here's what I have found, and what I think you will find if you listen to a bunch of videos and pay attention to what they used:

First off, this is simple. A V8 has only 4 explosions per revolution. 8 explosions every 2 revolutions of the crank (4 strokes) . A V12 has 6 per revolution, and 12 for every 2 revolutions. So it has a higher beats per revolution. A V12 will always sound higher pitched at any given RPM. You can only get a V12 to sound "so" deep. V8s will always sound deeper at any given RPM.

Mufflers are like a stereo speaker, you can kinda consider different mufflers like Woofers, midrange drivers and tweeters, but in reverse. The mufflers almost always subtract.

1] perforated "resonators" or glass packed mufflers, are like woofers. They tend to subtract high frequencies. They smooth the sound, but leave mostly bass. So, if you just had a speaker with only a woofer, that is how a large resonator muffler would sound by itself. This is why almost EVERY single person who installs some fancy stainless aftermarket exhaust complains about drone. There's no canceling of the lows. They flow right through at full volume.

2] chambered mufflers with walls for the exhaust to slam into and interrupt the flow, are more like midrange and tweeter speakers. By themselves, they cut bass, and sound tinny, trebly and on cars, a lot like a chainsaw. Here's some flowmasters, with apparently, no resonation to cut highs

3] this one's obvious, like any musical instrument, the larger the tubing and the more flare at the end (like a bell on a trumpet) the louder it can be,.

I think you need a balance of both #1 and #2. but need to know how your motor sounds with nothing, to know what to subtract or enhance. That's why I included the first video with the exhaust off. Doesn't sound at all like a V8 with wide open exhaust.

you might like this sound. I tried the Flowmaster DBX mufflers. They both cut bass and reduce the blatty ratty, metallic sound I hate. I kinda liked them with no stock muffling of any kind.

here they are with 2 foot long end tubes. The problem is, they are too long to fit in the back of the car and have long tubes like that. shorter tubes sound even more Bass-heavy. They do make a shorty version of this muffler. The shorty version "might" work in the rear muffler cavity.

here they are with long curved tubing, like as if you planned to put them in the middle of the car where the large second resonator blob is, and run several feet of tubing out the back. Not a bad sound, but too deep for me.

darn, I even bought an external mic with a fluffy windsock for my DLSR, but have no time to go out onto a country road, on a day that is not all windy, set it up on a tripod, and try to record this better.

I have not stood behind my own car and had someone drive away so I could simply hear it for myself. So I had my pal do it during lunch. I liked it-- so I told him to do it again so I could at least capture it on my iphone. Headphones will help the sound quality.